Lx570 driver headlight electrical issue (1 Viewer)

[highfructose]

I think I solved this but figured I’d post here in case someone else has had this issue…or someone else has it at some point.

My 2011 lx570 seemed to lose its ability to turn on the low beam driver side headlight.

Even with a new bulb it still wouldn’t turn on.
Fuse that runs specifically driver side low beam is fine (tested and swapped to right).
Relay, I assume, is fine because I think it runs left and right at same time.

Weirdly though, the day time running lamp is on on the drivers side even though it’s disabled at infotainment center.

The internet recommended wiring inspection and jiggle tests.

While looking around I noticed that the headlight assembly module for the driver side bundles its wires and routes under the windshield fluid washer Fill spout….and that bundle is damp under the spot.

There is an o ring on an elbow for that washer fluid fill spout and mine appears to have lost its ability to hold when full…and I recently filled it.

So I suspect, as these cars age, that fill spot o ring and bundle of wires under it might intermittently contribute to driver side headlight electrical issues.

 

[highfructose]

Letting the area dry and ensuring no more washer fluid drained into it didn’t solve the issue. I’m going to try to fix this and log progress here in the event it helps someone else later (or someone here as suggestions).

Issue:

Primary: low beam seems to be getting too little voltage…resulting in relatively dim (aftermarket) led ignition (I replaced the led momentarily with new and it didn’t solve)

Secondarily, as well as oddly, DRL is active in same (driver side) headlight (even though it’s turned off in the infotainment center).

Attempts at
Diagnosing
Note: you might consider getting some very heavy gauge jumper cables if diagnosing an issue around the driver headlight so you can, while the battery is out, still make the car function (turn lights on)…my normal 4 gauge (not 0/4) worked to turn the power on, but the car wouldn’t run…I don’t think the electrical system will like the reduced voltage/amperage it receives via these thinner cables for long…so I plan to try some 0 gauge…may allow for 2-3 times more amps to flow.

• (Have to disconnect and remove battery to get in here, 12mm for battery brackets, 13mm for my battery terminals)…I also took two mini Phillips head screws out of the main headlight connector bracket to remove it from the headlight assembly.
• Main big bundle in back of headlight is not drl headlight power supply…drl still received power with it disconnected….exceedingly difficult to separate connector due to 15 years of dust making it in between the plastic…patient flexing and hook pick pulling for it disconnected…this appears, instead, to run the drl…drl connector, likely because it’s so much smaller, was far easier, with patient flexing and hook pick pulling to remove
• 

• Main big connector appears to be related to, at minimum, side marker and low beam (this was the hard one to disconnect)…I suspect this is so large because it also controls/powers the auto leveling/turning low beam housing.

Daytime running lamp stays on even when I pull all headlight (high and low) fuses…as well as the daytime running lamp relay…

Google says slot 59 is the daytime running lamp fuse though that’s an empty use in my block…and I’ve read in this forum that the DRL just peel off voltage from the high beam circuit…

which means, considering pulling the high beam fuses leave the driver DRL on, it may be the case that a wire some place has rubbed and is allowing voltage to be delivered to the DRL…

need to identify which wire is hot on drl connector…then use that color wire and trace it back to wherever it’s getting power (I think)

 

[highfructose]

Step 2

• Two main prongs on driver side low beam are receiving 11v
• Drl is receiving an oscillating 6-15v

Gonna trace back the drl wires

 

[highfructose]

Letting the area dry and ensuring no more washer fluid drained into it didn’t solve the issue. I’m going to try to fix this and log progress here in the event it helps someone else later (or someone here as suggestions).

Issue:

Primary: low beam seems to be getting too little voltage…resulting in relatively dim (aftermarket) led ignition (I replaced the led momentarily with new and it didn’t solve)

Secondarily, as well as oddly, DRL is active in same (driver side) headlight (even though it’s turned off in the infotainment center).

Attempts at
Diagnosing
Note: you might consider getting some very heavy gauge jumper cables if diagnosing an issue around the driver headlight so you can, while the battery is out, still make the car function (turn lights on)…my normal 4 gauge (not 0/4) worked to turn the power on, but the car wouldn’t run…I don’t think the electrical system will like the reduced voltage/amperage it receives via these thinner cables for long…so I plan to try some 0 gauge…may allow for 2-3 times more amps to flow.

• (Have to disconnect and remove battery to get in here, 12mm for battery brackets, 13mm for my battery terminals)…I also took two mini Phillips head screws out of the main headlight connector bracket to remove it from the headlight assembly.
• Main big bundle in back of headlight is not drl headlight power supply…drl still received power with it disconnected….exceedingly difficult to separate connector due to 15 years of dust making it in between the plastic…patient flexing and hook pick pulling for it disconnected…this appears, instead, to run the drl…drl connector, likely because it’s so much smaller, was far easier, with patient flexing and hook pick pulling to remove
• View attachment 3866607

• Main big connector appears to be related to, at minimum, side marker and low beam (this was the hard one to disconnect)…I suspect this is so large because it also controls/powers the auto leveling/turning low beam housing.

View attachment 3866608

Daytime running lamp stays on even when I pull all headlight (high and low) fuses…as well as the daytime running lamp relay…

Google says slot 59 is the daytime running lamp fuse though that’s an empty use in my block…and I’ve read in this forum that the DRL just peel off voltage from the high beam circuit…

which means, considering pulling the high beam fuses leave the driver DRL on, it may be the case that a wire some place has rubbed and is allowing voltage to be delivered to the DRL…

need to identify which wire is hot on drl connector…then use that color wire and trace it back to wherever it’s getting power (I think)

Letting the area dry and ensuring no more washer fluid drained into it didn’t solve the issue. I’m going to try to fix this and log progress here in the event it helps someone else later (or someone here as suggestions).

Issue:

Primary: low beam seems to be getting too little voltage…resulting in relatively dim (aftermarket) led ignition (I replaced the led momentarily with new and it didn’t solve)

Secondarily, as well as oddly, DRL is active in same (driver side) headlight (even though it’s turned off in the infotainment center).

Attempts at
Diagnosing
Note: you might consider getting some very heavy gauge jumper cables if diagnosing an issue around the driver headlight so you can, while the battery is out, still make the car function (turn lights on)…my normal 4 gauge (not 0/4) worked to turn the power on, but the car wouldn’t run…I don’t think the electrical system will like the reduced voltage/amperage it receives via these thinner cables for long…so I plan to try some 0 gauge…may allow for 2-3 times more amps to flow.

• (Have to disconnect and remove battery to get in here, 12mm for battery brackets, 13mm for my battery terminals)…I also took two mini Phillips head screws out of the main headlight connector bracket to remove it from the headlight assembly.
• Main big bundle in back of headlight is not drl headlight power supply…drl still received power with it disconnected….exceedingly difficult to separate connector due to 15 years of dust making it in between the plastic…patient flexing and hook pick pulling for it disconnected…this appears, instead, to run the drl…drl connector, likely because it’s so much smaller, was far easier, with patient flexing and hook pick pulling to remove
• View attachment 3866607

• Main big connector appears to be related to, at minimum, side marker and low beam (this was the hard one to disconnect)…I suspect this is so large because it also controls/powers the auto leveling/turning low beam housing.

View attachment 3866608

Daytime running lamp stays on even when I pull all headlight (high and low) fuses…as well as the daytime running lamp relay…

Google says slot 59 is the daytime running lamp fuse though that’s an empty use in my block…and I’ve read in this forum that the DRL just peel off voltage from the high beam circuit…

which means, considering pulling the high beam fuses leave the driver DRL on, it may be the case that a wire some place has rubbed and is allowing voltage to be delivered to the DRL…

need to identify which wire is hot on drl connector…then use that color wire and trace it back to wherever it’s getting power (I think)

I traced wires back a little ways and everything looked good.

So tested a few of the pins on the vehicle side connector/harness for the DRL’s and low beams…and the vehicle seemed to be sending comparable signals to Passenger and driver headlight.

So I removed the driver headlight and plugged it into the harnesses on the passenger side (probably should have used extended probes to do this though it ended up being the case the headlight is likely faulty, so it was going to come out anyway)

(all those harnesses on the headlights essentially require you to depress the lever…and then use a screw driver to carefully pry/separate the harness/connector)

The driver side headlight when plugged into the passenger side harnesses exhibited the same issues: constant DRL and low voltage (I assume) to only partially ignite the led in the low beam.

It seems to be the case that there may be some internal issue inside the headlight l (headlight removal was straight forward…all 10mm mounting bolts accessible with a floppy ratcheting 10mm wrench and 10mm shortwell on very long extension-though with my ironman bumper a lot of the plastic has been removed so this may be more involved with a standard vehicle).

I attempted to disassemble the headlight assembly. It appears to have been sealed/glued shut (which makes sense)…it doesn’t look like it’s serviceable (the plastic gives before the sealant if you try to pry).

81170-60d31 Is the part number for driver side.

$828 plus the drive to and from the dealer…or $521 shipped from Lexus parts now…seems to be the best deal for it right now.